House Oversight and Government Reform Subcommittee on Government Operations Chairman John Mica holds a fake hand-rolled cigarette and a list of marijuana offenses during a hearing about drug laws. (Chip Somodevilla/Getty Images)

The District of Columbia's legislation to decriminalize possession of small amounts of marijuana appears unlikely to face harsh scrutiny in the Senate, where both Republicans and Democrats indicate they are inclined to defer to local officials.

"I kind of think maybe the District should make the decision themselves," said Sen. John McCain of Arizona, the second-ranking Republican on the Senate Homeland Security and Governmental Affairs Committee. "I may not agree with it, but they have an elected mayor and city council."

Similarly, Sen. Heidi Heitkamp, D-N.D., said she sees her role as a member of Homeland Security and Governmental Affairs as "very, very narrow" when it comes to D.C. Though she didn't know the specifics of the proposal, she said she thinks "the District is entitled to a whole lot of self-determination."

"For me to reverse what a city would do ... it would have to be something that I desperately disagreed with and believed had either constitutional problems or some very serious fiscal consequences that weren’t sustainable," Heitkamp told CQ Roll Call. Even GOP senators that are dubious about decriminalizing dope, such as Sens. Charles E. Grassley of Iowa and Jeff Sessions of Alabama, have not committed to trying to overturn the proposal to make possession of less than an ounce of pot a civil offense with a $25 fine, similar to a parking ticket.

Both are quick to decry marijuana's effects — Sessions thinks the District would be making a "mistake" — but they remain undecided about whether they would introduce a resolution of disapproval, which would need to be passed by both chambers and signed by the president. There have only been three such resolutions enacted since the District won Home Rule in 1973, and none have been enacted since 1991.

While a House Oversight and Government Reform subcommittee's recent hearing on the local legislation put the issue on many senators' radars, there are no plans in the works to convene a similar panel on the District's bill during its 60-day congressional review period.

In the Senate, it's Alaska Democrat Mark Begich who holds the gavel on the subcommittee with jurisdiction over the municipal affairs of D.C., the Homeland Security and Governmental Affairs Subcommittee on Emergency Management, Intergovernmental Relations and the District of Columbia. He told CQ Roll Call that no hearing is being planned "at this point."

Homeland Security and Governmental Affairs Chairman Thomas R. Carper, D-Del., said his views on decriminalization of marijuana are "evolving," but he does not intend to single out the D.C. bill for scrutiny. Ranking member Tom Coburn, R-Okla., said he had not looked into the proposal yet.

Carper and Begich have co-sponsored legislation to give D.C. budget and legislative autonomy from Congress, and other Democrats on the committee indicated they want to respect the District's autonomy by not intervening.

"If they want to decriminalize small amounts of marijuana in the District of Columbia, I think the government of the District of Columbia ought to have the right to do that," said Sen. Claire McCaskill, D-Mo. "I'm not there for decriminalization writ large," she continued, adding that she thinks marijuana may have medical uses, and the "jury is still out" on Colorado's experiment with legalization.

Sen. Carl Levin, D-Mich., told CQ Roll Call that he had no problem with decriminalizing small amounts of marijuana "period," and would probably vote for decriminalization back home in Michigan, "so I don't have any problem with D.C. doing it."

Proponents of the decriminalization plan and self-determination for the District say Sen. Rand Paul is the panel member most likely to intervene in District affairs, pointing to his actions in 2012, when he proposed a handful of amendments relating to gun control and abortion laws for a D.C. budget autonomy bill that prompted Senate leaders to pull the proposal.

Drug laws, however, are an area where the libertarian-leaning 2016 hopeful is unlikely to intervene. The Kentucky Republican has introduced legislation to relax federal sentencing laws, and indicated he believes penalties for pot are too harsh.

“You know, it’s interesting; these guys are all about no federalism and state and local control, until they’re not,” McCaskill said.

The D.C. Council and Mayor Vincent Gray also considered decriminalization a matter of social justice. Rather than approaching the pot policy under the guise of marijuana being a safe substance or as a gateway for recreational use, proponents pushed to stop selective policing of pot in the District.

The bill was motivated by an American Civil Liberties Union study showing that Washington, D.C., had the highest per-capita marijuana arrest rate in the nation between 2001 and 2010, and that blacks were eight times more likely to be arrested than whites.

Opponents like Sessions think those efforts might be misguided. The senator looks back proudly at his efforts, alongside President Ronald Reagan, to “create a hostility to drug use” in the early 1980s.

"The result was enormously beneficial to everybody, but particularly young people," Sessions said, referring to his work as a U.S. attorney. "Use went down substantially and crime went down. Murders today are half what they were in 1980."

Sessions fears President Barack Obama damaged those efforts with his recent statements that marijuana was not more harmful than alcohol.

"I just don't think people understand the damage [of] the president's statement, where he made light of marijuana use," he said, adding, "but it looks like, you know, there's momentum around the country."